Thread-rolling appliance



NOV- 27, 1951 T. K. AFFLECK I THREAD-ROLLING APPLIANCE 2 SHEETS-SHEET l Filed Dec. 24, 19,47

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THREAD-ROLLING APPLANCE Filed DBC. 24, 1947 2 SHEETS--SHEET 2 rNveN'l-ale E., wmmmv www Patented Nov. 27, -1951 THREAD .--ROI'ILING APPLIANCE Theodore King Affleck, London, England, as-

signor to Acton Bolt Limited, London, England, a company of Great Britain Application December 24, 1947, Serial No. 793,593 In Great Britain January 3, 1947 2 Claims. (Cl. 80-6) The invention has reference to thread-rolling appliances of the kind typified by those described in British Patent No. 499,277, comprising a pair of free and independent screw-threaded rolls rotatably mounted on a carrier which is adapted to be moved laterally towards a revolving work-piece to cause the latter to be engaged between and to rotate said rolls, resulting in the formation of a continuous screw-thread upon the workpiece. The object of the invention is to provide an appliance, of the aforesaid kind, which can be employed for the simultaneous production of a rolled thread upon each of two parts of a work-piece which are of different diameters.

In a thread-rolling appliance in accordance with the invention, the thread-forming surfaces of the two rolls are oiT-set one in relation to the other, to an extent equal to the axial distance between the parts of the work-piece which are to be threaded, the arrangement being such that when engaged with the work-piece each roll produces a thread upon one of the parts thereof, the pressures of the rolls balancing one another on opposite sides of the work-piece.

The invention is primarily applicable to threadrolling tools for use on work where the diierence in diameter of the two parts to be threaded simultaneously is small in comparison with the diameter of those parts.

A specic embodiment of the invention adapted for mounting on the saddle of a lathe, is illustrated by the accompanying drawings, of which:

Figs. l and 2 show respectively a side elevation and a front elevation of the tool;

Fig. 3 shows a section on the line III-III in Fig. 2; and

Fig. 4 shows a section on the line IV-IV in Fig. 1.

The tool comprises a carrier formed by a substantially rectangular block I0, a two-jawed bracket II pivoted to the carrier block I on a pin I3, and a pair of thread-forming rolls I2, I2 rotatably mounted in the jaws of the bracket II. The rolls I2 are xed on spindles I4 free to rotate in bearings in the jaws of the bracket I I, which are each bifurcated to accommodate the rolls.

It will be seen from Fig. 2 that the two rolls I2, I2 are not mounted with their thread-forming surfaces opposite one another, as in a normal thread-rolling appliance, but that they are instead mounted with their thread-rolling surfaces axially offset from one another in accordance with the axial distance between the two parts of the work-piece to be threaded simultaneously.

The two thread-forming rolls I2, I2 are thus adapted, when -the tool is moved laterally to engage a revolving work-piece, to roll a continuous thread on each of two axially separated but coaxial parts of the work-piece, each roll being effective to roll the thread on one of the two parts.

It will be understood that, in order that the radial pressures exerted on the revolving workpiece by the opposite rolls may balance each other without applying excessive torque to the work-piece or to the tool-holder, it is desirable that the parts of the work-piece on which threads are to be rolled should be separated by the minimum axial distance.

The diameter and thread-pitch of each of the two thread-forming rolls I2, I2 is selected in accordance with the diameter of that part of the work-piece on which that roll is intended to form a thread, as with a normal thread-rolling tool, and it will be obvious that the diameters of the parts of the work-piece which are to be threaded may be either the same or different. If desired different forms of thread, or diierent pitches of thread, may be applied to the said parts of the work-piece.

A small degree of axial play is permitted both to the bracket II along its pivot pin I3, and to the spindles Ill carrying the threaded rolls I2. A helical spring I5 is provided for taking up the play of the bracket II and returning the bracket to the same axial position whenever the appliance is withdrawn out of engagement with the work-piece, while leaf springs IB have a similar function with respect to the threaded rolls I2.

It will be understood that, for those classes of work which require to have threads formed thereon in accordance with the conditions specified, the invention is effective in bringing about a substantial saving in time and cost by permitting the performance in one operation of work what has heretofore required two such operations.

What I claim as my invention and desire to secure by Letters Patent is:

1. A thread-rolling appliance comprising supporting means, and two rolls journalled in said supporting means for free rotation about parallel axes, said rolls being spaced apart to permit a Work-piece to be engaged therebetween by lateral movement, each of said rolls having a thread-forming surface, the thread-forming surfaces of the respective rolls having different diameters and being axially olset to an extent to a tool support, a two-jawed bracket pivotally 5 mounted on the carrier, the thread-forming rolls being journalled oney in each jaw of the bracket;

THEoDoRE KING AFFLECK.

REFERENCES CITED The following references are of record in the le of this patent:

Number Number UNITED STATES PATENTS Name Date Gould J JunellI 1940 Plagemannet a1. Feb. 29, 1944 FOREIGN PATENTS Country Date Great Britain Jan. 25, 1892 

